WEDNESDAY, Feb. 4, 2015 (HealthDay News) -- Researchers say they've developed a device that can deliver drugs to pancreatic tumors in mice, and they hope it will one day become a valuable tool in the treatment of one of the deadliest cancers in people.

Details about the device's cost and its effect on people aren't known, and scientists didn't study whether the mice actually lived longer after being treated. Still, the device has the potential to make a difference in human patients, said study co-author Joseph DeSimone, a professor of chemistry at the University of North Carolina at Chapel Hill.

"We used a drug that doesn't normally work that well and were able to make tumors shrink because of the way we delivered it into the tumors," said DeSimone.

But several researchers not involved with the study were skeptical of its cancer-fighting potential for people.

The American Cancer Society (ACS) estimates that almost 50,000 people in the United States will develop pancreatic cancer and more than 40,000 Americans will die from the disease this year.

"Pancreatic cancer is so difficult to treat for a number of reasons," said study co-author Dr. Jen Jen Yeh, an associate professor of surgery at the University of North Carolina at Chapel Hill. "Most patients have no warning symptoms until the tumor is advanced," she said.

In addition, it's difficult to penetrate tumors with medication because they lack blood vessels, and the tumors spread quickly, according to Yeh.

In the new study, researchers tested a version of their device -- which is just 6 millimeters in diameter -- on mice with human pancreatic tumors.

The device is implanted through surgery "and fed medicine and electrical power through a port that is accessed outside of the body, similar to an infusion pump or insulin pump," said medical student James Byrne, who works in DeSimone's lab. "We can design it to be powered by a battery or as a plug-in to an electrical outlet."

Other mice received chemotherapy intravenously like people do. The researchers found that tumors shrunk in all the mice with the device and in none of the mice that got the IV treatment.

The researchers didn't analyze how long the mice lived.

Even if the device works in people, there are limitations. It can't treat widespread cancer, but it could potentially be used to provide relief via medication to patients, DeSimone said.

And it might be used to shrink tumors so they could be removed by surgery, the researchers suggested. They also think it could be used to treat other types of tumors such as those from breast cancer and head and neck cancer.

Dr. Aaron Sasson, chief of gastrointestinal surgery at the University of Nebraska Medical Center, was cautious about the research. "If the technology works, it would only benefit a small percentage of patients," he said. Sasson explained that patients with pancreatic cancer are especially likely to die from cancer that spreads, not the original tumor itself.

Plus, he added, "The list of treatments that are effective in mice but not in patients is very long. They have a long way to go."

Dr. Allyson Ocean, an associate professor of clinical medicine at Weill Cornell Medical College and New York-Presbyterian Hospital, agreed that the routine spread of pancreatic cancer -- often prior to diagnosis -- is an important caveat to the potential usefulness of the device.

"Therefore, I do not believe that this form of drug delivery will likely translate into significantly improved survival results when the device is tested in humans," she said.

However, Ocean suggested that it could still be helpful in other ways, such as reducing pain by shrinking the size of tumors.

The study authors, who haven't yet figured out a cost for the device, expect they may be able to test it in people within the next couple of years.

The study appears in the Feb. 4 issue of Science Translational Medicine.